[artdutra04]

Besides cost and safety already mentioned, the engineering reason behind Li-Ion batteries not being suitable for FRC are the high current spikes we see.

All batteries are rated with a "C" rating that is a multiple of their rated current capacity. The "C" rating is what determines what is the highest amount of current that can be used to either charge or discharge the cell. For example, a 800 mAh 3.7v Li-Ion cell rated at max charge 1C and max discharge 2C can be charged at a rate no faster than 800 mA and discharged at no more than 1600 mA.

In general, Li-Ion batteries are never rated for high discharge capacities. Lithium Polymer batteries are better, and can have ratings in the double-digit C range, but these are not cheap. For FRC, a single Li-Po battery capable of meeting our needs would likely be at least $150.

Lithium Iron Phosphate chemistry shows potential, but is still too new and costly. LiFePO4 has lower capacities per kilogram than Li-Po, but is inherently a much safer technology. It will not explode or catch fire if mishandled or abused.